Eva Risztov, of Hungary, held on for gold in the Olympic marathon after showing the courage to break away from the lead shoal about half-way round the fifth of six laps of The Serpentine in Hyde Park.

Risztov took the crown in 1hr 57.38.2 ahead of Hayley Anderson (USA), just 0.4sec away and Martina Grimaldi (ITA), who took bronze a stroke ahead of world champion Keri-Anne Payne (GBR).

In a sport where comebacks have rarely ended in success in 2012, Risztov, disqualified for impeding rivals at the world championships last year, bucked the trend.

Another example of a pool swimmer clobbering the ambitions of pure open-water specialists, she led for great swathes of the race, pulled the heart out of the pace on the fifth lap and had what it took to keep the purists at bay.

Risztov, who won three silver medals at the 2003 world championships in Barcelona but fell shy of the Olympic podium in the pool, both at Sydney 2000 and Athens 2004, quit in 2005.

Watching Beijing 2008 on the television she had second thoughts and returned to her local club. "I finished because I wasn't happy with the results but after three years I felt I missed out on the Olympics and I was capable of a medal," she said here today.

"I didn't think about it to begin with. I got a telephone call from the manager of the swimming club in Debrecen asking me to begin swimming again so I began again."

The 26-year-old trained in the pool but opted for the 10km after spotting the chance of a new beginning when the marathon joined the Olympic party in 2008.

Risztov did not leave her pool racing days entirely behind her. Last week, she finishing 16th in the 400 metres freestyle, 13th in the 800 freestyle and 15th in the 4x100 freestyle relay as a warm-up for The Serpentine today.

Relatively new to the marathon, she used her superior speed from the pool to get in the lead early where she could not get in trouble, then stayed there for much of the race, at one point flipping to backstroke to check the opposition and pause to take a sip of energy drink.

"I decided to make it a very clean race today. If I led, no-one could say I did anything," she said. "That was my tactic and if I could not win from first place, my mind would have been clear. This is the toughest way to win but I decided to follow this tactic because this is the only way to win clearly. That is what I trained for."

After breaking away with just over a lap to go, she established a lead of between 7 and 10m for much of the last 1500m and fought off a late charge from Anderson, whose sister Allysa won a relay gold in the 4x200m as a heats swimmer for the US in the pool. The marathon pair sprinted to the line but it was Risztov's day.

"After the Shanghai race I did not understand exactly why I was disqualified but I am not very experienced in open water swimming," she said. "This race is only the seventh of my life. I hope from now I will become a member of the elite in open water swimming."